docs: def start_http_server(self, port, host='0.0.0.0', endpoint='/metrics'):
          """
          Start an HTTP server for exposing the metrics.
          This will be an individual Flask application,
          not the one registered with this class.
  
          :param port: the HTTP port to expose the metrics endpoint on
          :param host: the HTTP host to listen on (default: `0.0.0.0`)
          :param endpoint: the URL path to expose the endpoint on
              (default: `/metrics`)
          """
  
          if is_running_from_reloader():
              return
  
          app = Flask('prometheus-flask-exporter-%d' % port)
          self.register_endpoint(endpoint, app)
  
          def run_app():
              app.run(host=host, port=port)
  
          thread = threading.Thread(target=run_app)
          thread.setDaemon(True)
          thread.start()